This study examined the use of collaborative interdisciplinary authentic tasks as a context in which learners develop and use self-regulated learning (SRL) processes. Participants included sixty-four students from a U.S. middle school whose residents are largely from low-income families. Students worked in groups to design and carry out an authentic, interdisciplinary project over a 9-week period. A Hierarchical Linear Modeling (HLM) analysis suggested that students' individual SRL increased over the course of the project and that co-regulated learning (CRL) moderated this relationship. Furthermore, one group was selected as an exemplar case to provide an explanation of how co-regulation occurred and influenced SRL in this collaborative group. Theoretical and practical implications of the research are discussed.